A new poll shows American opinions on Iraq have shifted a lot in recent weeks. The biggest change came for people who were opposing U.S. involvement.

Last month, the USA Today-Pew Research Center poll on Iraq showed 55 percent said the United States did not have a responsibility to intervene to stop the violence.

Now only 41 percent say the U.S. does not need to take action, while 44 percent say it does and 15 percent still don't know what to do.

Most Americans, 54 percent, approve of U.S. airstrikes against Islamic State fighters. But a majority are also afraid the U.S. will get sucked back into another long conflict in Iraq.

CBN News Anchor John Jessup spoke with Erik Prince, founder of the private security contracting firm Blackwater, for his analysis on the ISIS reign of terror in Iraq. Blackwater was heavily involved in the Iraq War.

Prince said Iraq is in crisis today partly because of a failure in U.S. leadership to aid the transition of power away from divisive Iraqi Prime Minister Nouri al Maliki.

Islam: Religion of Peace or War?Arabic scholars bring you a historical and shocking narrative on the tenets of Islam and the life of its founder. Know the truth. Download now.

"There is real evil in the world. There's no way to call it anything but pure evil," Prince said of the terrorist group. He explains what needs to happen in Iraq for ISIS to be defeated.

How did Iraq get this point? Prince explains this and how the U.S. should help now.

"Thousands of dead Americans, dead allies. Tens of thousands of wounded all for very limited effects," Prince said.

"And really I come back to that window of opportunity four years ago, that diplomatically, Malaki lost the election. He should have been forced out. And he wasn't," he continued. "Huge failure on the part of the Obama administration."

But Prince said Iraq has just turned an important corner with the selection of a new prime minister. He said the main job will now be to convince Sunni Iraqis to join the government and reject the ISIS terrorists who they've been helping.

"Military victories drive diplomatic breakthroughs. And if he's able to cut off and crush the ISIS capability to rain terror, and I think if he reaches out to the Sunni tribal leaders out in al Anbar province and say, 'Look, we want you as part of Iraq. We're not here to oppress you and seek retribution,' that's probably the best way forward," Prince said.

The former CIA contractor said there are already some hopeful signs that the Islamic State can actually be driven out in the end.

"I think the Sunni tribes even will start to marginalize and cut off the ability for ISIS to operate," Prince said.

"There's been fighting already in some of the cities that have allegedly been conquered between the tribes who are not crazy and the crazy ISIS guys who are trying to drag them back a thousand years," he said. "So there's going to be some pretty significant friction."